Speed cup balancing machine



May l1, 1937. R. DE WITT SPEED CUP BALANCING MACHINE Filed Nov. l, 1935 3 Sheets-Sheet l u, 1997. R, DE WITT n 2,979,902

SPEED CUP BALANCING MACHINE Filed NOV. l, 1935 ,3 SheetS-Sheell 2 Kw y-752 May l, 1937. R. DE Wn-T 2,079,902

SPEED CUP BALANCING MACHINE Filed NOV. l, 1935 3 Shee'LS-SheeJ 5 N mi f' ll Patented May 11, i937 SPEED CUP BALANCING MACHINE Reinhold De Witt, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 1, 1935, Serial No. 47,754

14 Claims.

This invention relates to a process and a machine for balancing a freely swinging element and has been designed particularly for balancing the speed cup of a magnetic measuring instrument.

The object of the invention is to eiect a more accurate balancing of the speed cup, to balance the cup in a way which shall be permanent, to save time in the process of balancing, and to avoid cut and try procedure.

A further detail, and one useful not only in this machine but elsewhere, is the provision of a novel form of oscillating bearing to reduce friction at the bearing support.

Other objects and advantages will be understood from the following description.

The invention is illustrated in the accompanying drawings in which:

Fig. i is a top plan View, partly in section, of the novel machine.

Fig. 2 is a long section on line 2-2 of Fig. l.

Fig. 3 is an elevation, partly broken away, as seen substantially from the left end of Fig. 1.

Fig. 4 is a View as seen from line 4 4 of Fig. 1.

Fig. 5 is a view as seen from line 5-5 of Fig. 2. Figs, 6, 7 and 8 are perspectives of details. Figs. 9, 9a. and 9b are diagrammatic views. Referring by reference characters to the drawings, numeral is the base of the machine. The base has an end pedestal I3 provided with a longitudinal slot l5 guided by an elongated lug i1 extending above the base and secured by fastening means i9. The pedestal is secured to the base by fastening means 2| extending through slots 23 whereby the pedestal may be longitudinally adjusted to a limited extent and secured in its position of adjustment. A pivot bolt 25 is secured in the top of the pedestal and serves as the fulcrum for a bell crank lever 21. A lug 29 secured as at 3| serves as al limiting stop for the work end 33 of the lever.

A second pedestal is Shown at 35. Its position on the base must be accurately related to the first pedestal. This is accomplished by a slot and lug expedient marked 31. This pedestal is secured by fastening means 39. Adjacent the upper end of the pedestal is a through passage to provide reciprocatory support for a shaft 4|. This shaft is formed with a head 33. A link (i5 connects the end of the shaft il and the end of lever arm 33. The head 43 is formed with an opening 41 for a purpose to be explained. A stud 49 is located in a hole 5I of the pedestal 35, its head 53 being within opening 61 when the head is in abutment with the pedestal as shown.

Numeral 55 is used to designate a third pedestal.

It is located on the base in alignment with the other pedestals by similar positioning means marked 51. It is secured to the base by fastening means 59. Fig. 7 shows this pedestal in perspective. It is formed with an arcuate through opening 6l and a tubular opening 63 for a bearing pin 65, the latter secured by a screw B1 through an opening 69.

A fourth pedestal marked 1| is secured to the b-ase by fastening means 13. Alignment is assured b-y a similar expedient designated by numeral 15. This pedestal has an arcuate opening 11, like 6| of pedestal 65. It has a tubular opening supporting a rotatable spindle 19. Adjacent the inner face of the pedestal the spindle is of non-circular outline as shown at 8|. A crank 83 having a handle 85 is carried by the part 8| of the spindle. The right end oi the spindle 19 constitutes a second bearing pin 80 and is in alignment with the bearing pin 65. Two swinging members 81 and 89 have the overlapping extremities 9| and 93 of end arms 92 and 94 journaled on pin 80 and similar overlapping extremities 95 and 91 on end arms 9B and 98 are journaled on pin 65. Each swinging member in addition to its end arms journaled as shown has an intermediate arm as at 99 and |0|. Each intermediate arm is apertured to receive a die |03 designed to receive a punch |05. There are two such punches carried by axial extensions |00 and u |02 of arms 96 and 98. Fig. 1 illustrates the construction and mounting of the punch. 'I'he arm extension is apertured and carries therein a sleeve |01 within one end of which is an inner sleeve |09 through which slides the punch spindle Slidable in the opposite end of sleeve |01 is a stern ||3 having a rounded head ||5. A coil spring ||1 engages the arm extension and the head |I5. Stem ||3 at its inner end is axially bored and threaded as at I I9 to receive the inner end of spindle The spindle has threaded thereon a nut |2| and a spring |23 engages the nut and the inner end of sleeve |09. The extensions |00 and |02 of the two swinging members move in the arcuate slot 6| as the members rock on the bearing pins 65 and 80. The swinging members have other axial extensions and |21 movable in the arcuate slot 11 of pedestal 1|.

Secured by fastening means |33 to pedestal 1| is a plate having a vertical slot |31 within which slides a sliding member |39. Adjacent plate |35 and the vertically sliding member |39 is a cam plate |4|. It is immovably connected to sliding member |39 by pins |43, so that the cam plate and sliding member |39 move together, vertically guided by the slot in end plate |35. The cam plate has a horizontal slot |55 (see Fig. 3) to receive pins |51 extending from the ends of extensions |25, |21. It will be obvious that the pins |41 may travel horizontally in the slot |65 and thus rock the swinging members when the cam plate is reciprocated. Fig. 3 shows three positions of the cam plate, an intermediate position in full linespand extreme upper and an vextreme lower vposition in dash lines. shown by the use of primed reference characters. It may be here explainedgthat when .the cam plate is in the uppermost position the swinging members are rotated by the pinsv |41 to horizontal alignment as shown byFig. 4.. As'the cam plate descends the swinging members rock toward each other. Whenin. their position of horizontal alignment, the head H5 of the punch assembly associated with extension |92 is in alignment with the hole ||1 in the head'43. The purpose of this will appear hereinafter.

The cam plate is reciprocated by rotation of the crank handle.'85. .The structural arrangement to so operate is as follows: On the side of pedestal 1| opposite the crank 83 the stem 19 is provided with a rigid head |139. Two pins |5| and |53 project from the head |49 andenter cam slots |55 and |51 respectively. Rocking oi the crank handle causes the head |49 to rotate and its pinand cam relation to the cam plate effects a vertical reciprocation of the latter, which reciprocation causesrotation of two swinging members by the movement of pins |41 in the horizontal slot |45. An examination of Fig. 3 will show that the pins 5| and |53 act successively in their respective slots, this being arranged to obtain an easy .and gradual moving of the cam plate.

More specically and comparingFigs. 3, Land 5, it will be observed that when the parts are positioned as in Fig. .4, pin 5| is in the enlarged opening at the end of slot |55 and when the crank 83 and plate |49 begin their rotation this pin moves without function until it reaches the edge of the narrow part of slot |55, a position substantially that of the full line showing of Fig. 3. In the meantime, during this idle movement of pin |5|, pin |53 has been pressing against the lower edge of the narrow part of its slot |51 and therefore pushes the cam plate downwardly, thus rotating the swinging arms 81 and 89 through the instrumentality of the pins |51 engaging the walls of horizontal slot |45. During the second part of the rotation of the crank 83 the pin |5| moves in the narrow part of slot |55 pushing the plate lfii downwardly-the pin |59 then moving without function in the enlarged end of slot |51.

Between pedestals 55 and 1| is a-fth pedestal |59. It is mounted on base for guided transverse adjustment as at il'i. APedestal |59 has end posts |63 and |65 to which is secured by fastening means |91 their metallicA strips |69. To the upper end of each metallic strip is secured as at I1! a holder |13 as shown best by Fig. 6. The holder has transversely disposed arms |15 between which a spool |11 is held by the conical ends of pins |19 threaded into the arms. The spool is thus freely rotatable on the coned ends of the pins. A speedometer Vspeed cup to be balanced by the operation of the machine is shown at 8| located between the intermediate arms and the end arms 9E and 98 of the swinging members. The stem of the cupmarked |83 The changed position of the pins |41 .is

is supported on the two spools and in the axis of pin 65. In fact the end of the pin G5 is provided with a flat jewel and engages, in. thrust relation, the spindle |83. It will be seen that the clockwise rotation of handle 21 as in Fig. i will push the head 53 toward the left. This movement is operable to push the heads H5 and thereby the punches |95 against and through the bottom of the speed cup and into the openings |93. The discs sopunched out fall to a guiding plate |55 and escape through opening |81 in the base.

As will be explained below, it is necessary to reduce to the minimum the friction between the spools and the speed cup spindle so that in the event of any unequal distribution of weight the speed cup will rotate to equalize the weight on the two sides of the vertical diameter of the cup. To that end a suitable synchronous motor |89 is attached to the base as at |9|. It drives a shaft |93 coupled as at |95 to a shaft |91 journaled in two arms |99 and 29| extending upwardly from the fifth pedestal. This shaft |91 has secured thereto as at 293 a multiple cam 255 located between the sheet metal strips |55 and engaging abutments 291 carried thereby. In consequence, the strips |59 and the spools |11 supported thereby are constantly moved toward and from each other. In this way the vibrating support for the speed cup spindle reduces friction to a substantially irreducible minimum. The movement of the spools simultaneously toward and from each other prevents any tendency to shift the spindle and its cup axially.

To the crank 93 is secured a pointer |259 extending axially toward the speed cup.

.Fig 8 shows a U-shaped spring 255. It is secured to base at 292. Its arms engage the adjacent sides of parts |25 and |21. As the swinging members 81 and 89 are folded toward each and as the pins |131 move toward each other in the slot |55, the spring arms are tensioned. The spring energy thus stored in the arms is of assistance in rotating the swinging members back to their positions of horizontal alignment.

The operation of removing material to give an accurate static balance is as follows: With the synchronous motor in operation and with the speed cup spindle supported on the vibrating spools, the cup rotates until its out of balance weight is at the bottom of the vertical axis. The crank handle 85 is then rotated to raise the cam plate to its uppermost position, the position shown by the upper dotted lines of Fig. 3. This raises the swinging members to a position of horizontal alignment as in Fig. 4. When so positioned the arm extension |02 carries the punch assembly to a position in which the head H5 registers with the opening 51. The arm 21 is now rotated clockwise (as in Fig. l), thus advancing the head 53 to the left. Since the head H5 of the punch associated with arm extension |2` is opposite the hole 41, its punch is not operated. However, the other punch (the one carried by extension l) is advanced by the advance of head t3 in engagement therewith and a disc is punched out on one side of the vertical axis of the bottom wall of the cup and on the horizontal axis thereof. The disc escapes out through opening |31. Fig. 9 shows the operation just described, W2 representing the original out of balance weight and W the hole where the disc is punched out. The balance thus disturbed causes the cup to rotate and assume a new position of rest in which the point W moves up through an angle a (see Cil Fig. 9a). The crank handle 85 is then rotated until its indicating pointer is directly opposite the hole which has been made in the cup. Such turning of the crank handle has reciprocated' the cam plate and turned the swinging members so that the hole 41 is no longer opposite one of the heads H5. The handle 21 is then again rotated with the result that two additional holes W4 W4 are punched in the cup (see Fig. 9b). This operation has produced an accurately balanced speed cup, and has done so with a minimum expenditure of time. It avoids the dust resulting from the grinding process which it is intended to replace, thus further avoiding the need of blowers and cleaners to remove the dust. It has been found convenient to slightly incline the base to maintain contact between the end ofthe cup spindle |83 and the thrust bearing at the end of pin 65.

VIn the event that after punching the rst hole W the pointer cannot be made to register with the opening so punched, the cup may be turned to bring the punched hole to the upper end of the vertical diameter when a second single hole may be punched in the horizontal axis by bringing the swinging arms to horizontal alignment. The cup may then be allowed to swing to a new position of rest after which two holes are punched as before. l v

To make the disclosure somewhat clearer, the following mathematical deduction will show how the cam slots are made. Referring to Fig. 9 we may assume that the cup to be balanced has been supported by its spindle and that its un-` balance causes it to rotate until its unbalanced weight W2 is at the bottom of the vertical aids. The instrument is then manipulated and a hole W is punched in the horizontal axis as explained above. This step is the equivalent of adding a weight W1 (equal to the weight of the material removed at W) on the horizontal axis on the opposite side of the vertical axis of the disc. The disc then swings until the points W2 W W1 assume the positions shown in Fig. 9a, the new unbalance being represented at W3. It is possible to cut out material at W3 to balance the disc and this process has been used. At present it is preferred to punch two equally dimensioned holes at W4 W4 at an angle r from the vertical as shown by Fig. 9b. The turning of the crank 8.3 so that the pointer is opposite the new position of W` causes the cam slot to bring the punches to the correct position for punching holes W4 to eiect the balance.

As shown on Fig. 9a, let a represent the angle through which the disc rotates after punching hole W. Angle b, its complement, is the angle between the radius through W1 and the vertical ax1s.

From Fig. 9a it will be seen that Since X=R cos a and y=R sin a W1R cos a=W2R sin a W1 cos a=W2 sin a cos a W2: W1

sin a Since X1=R sin a+Y1=R cos a W3==W1 sin 1H-W2 cos a cos a 3 cos b Therefore, if a balance were to be secured by removing material at the bottom of the vertical diameter, automatic means should be provided such that the depth of cutting will be variable and determined by the weight of the disc rst punched out and the angle a through which the disc swings so that W3 the weight removed shall equal cos b As stated above, in accordance with the present invention it is proposed not to remove an amount of` material at W3 but to punch out equal discs at W4 W4 as on Fig. 9b. In this case it is not the amount of cutting determined by automatic mechanism but the angular position of the holes punched. 1* has been used to designate the angle between the vertical axis and the radii through W4, the size of the punch for W4 W4 being the same as for W.

The cam outline whereby, when the handle is rotated to position the pointer opposite the changed position of hole W such that the punches shall assume positions to punch holes at W4 W4 and balance the cup is therefore formed in accordance with the formula cos There are limitations to the above process of vbalancing dependent upon the original amount of unbalance which at times requires a slightly different set of steps. In theory from the formula given above r becomes o when b is equal to 60 when b=60 W=W tan of 60=l.73W

Therefore, if the amount of unbalance is as much as 1.73 times the weight W the process fails theoretically.

The above process requires modification also because of mechanical limitations in the event that the unbalance is as much as 1.54 times the weight W. This is due to the fact that the original unbalance may be so great that the removal of weight W causes the disc to rotate so slightly that the holes to be punched overlap. Also, be-

cause of interference of the punch mechanism itself, the angle r must not besmaller than 2321.

Practically, therefore, the unbalance to be corrected by the method rst described is limited to cases when W2 is not more than 1.54 times the weight W. By the modified process used when W2 is greater than 1.54 W after punching out W and nding that W2 is greater than W 1.54 the weight W2 is in effect reduced by an amount W. This is done, as explained above, by rotating the disc to bring W2 to the horizontal, and then punching a second time, whereby a new reduced unbalance (W2-W=W5) r-esults. The amount of unbalance capable of correction by this modified process is 2.54 W since the unbalance capable of correction is W (an unbalance caused by punching W at W2 moved to the horizontal axis) and the former maximum W 1.54 which together equal 2.54 W.

By this simple process, therefore, an unbalanced speed cup or any similarly fully rotating element may be quickly and accurately balanced. It requires no cut and try methods and the correction is of a permanent character.

In some of the following claims the angle between the vertical axis and the radius through the hole W in its position of rest is designated by b and the angle between the vertical axis and the radii through holes W4 is designated by 1.

I claim:

1. The process of giving static balance to an unbalanced element consisting in mounting said element for free rotation to localize its unbalanced Weight in its vertical axis, removing material from one side of said axis`,'permitting the element to swing to a new position of rest and removing material to balance the element, the region of removal being determined by the mass of material first removed and the extent of rotation resulting from such first removal.

2. The process of balancing an out of balance freely rotatable element comprising removing material from a position in its horizontal axis at one side of its vertical axis, permitting said element to rotate after said removal of material and subsequently removing material partly from each side of its vertical axis, said positions of subsequent removal being determined by the mass of material first removed and by the rotation of the element after said removal.

3. The process of giving a static balance to an out of balance element consisting in mounting the element for free rotation whereby its out of balance weight lies in the vertical axis, removing a predetermined mass of material from one point in the horizontal axis, permitting the element to rotate through an angle to a new position of rest and subsequently removing material at two positions, the radii through saidv positions forming equal angles with the vertical axis and said positions being .determined by the mass of material first removed and by the angle of rotation subsequent thereto.

4. The process of givingv an unbalanced element a static balance consisting in mounting the element for free rotation whereby its out of balance weight lies inthe vertical axis, removing material from a horizontal axis, permitting the element to rotate to a new position of rest, removing material from two positions one on each side of the vertical axis at radial distances equal to the radial distance of the rst removal of material and on radial lines making equal angles with the vertical axis, said positions determined by the mass of material first removed and by the resulting angle of rotation of the element.

5. The invention dened by claim 4 wherein the location of the positions for second removal of material is determined by the formula 1 'z ESs-b where b equals the complement of the angle through which the element rotates and 1 the last mentioned angle with the vertical axis.

6. The process of giving static balance to an unbalanced element comprising mounting the element for free rotation, removing material at a point in its horizontal axis, rotating said element to bring said point to the uppermost point of the vertical axis, again removing material from the horizontal axis at the same radial distance, permitting the element to rotate to a new position of rest, and subsequently removing material at two positions, one on either side of the vertical axis, the radial lines of said positions making equal angles with the vertical axis and the radial distance of each being the same as the radial distance of said point.

'7. The process of effecting a static balance in a freely rotatable element consisting in permitting the element to rotate to a position of rest, punching a hole in the horizontal axis, permitting the element to rotate to a second position of rest and punching two holes one on each side of the vertical diameter, the location of said last-named holes being determined by the formula 8. In a machine to give static balance to an unbalanced element, means to support said element for free rotation, means to punch holes in said element simultaneously on both sides of its vertical axis, and means whereby one of said punch means becomes inoperative in a predetermined position of said punch means.

9. 'Ihe invention defined by claim 8, said rst named supporting means comprising a plurality of supporting members and mechanism to move said members simultaneously toward and from each other.

10. In a machine to give static balance to an out of balance element, means to support said element for free rotation, swinging members, punches carried thereby adapted to punch holes in said e-lement, mechanism to rotate said swinging members to locate said punches in predetermined positions, said punches being reciprocable and having heads, and axially movable means to engage said heads and reciprocate said punches. y

11. The invention dened by claim 10, said movable means having an opening therein whereby in one of said predetermined positions one of said punches is not reciprocated by the movement of said movable means.

12. II"he invention defined by claim 10, said mechanism comprising a rotatable plate provided with pins, a reciprocable plate having cam slots receiving said pins, said reciprocable plate also having a horizontal slot, said swinging members having pins received within said horizontal slot.

13. In a machine to give static balance to an out of balance element, means to support said COS I:

element for free rotation, swinging members, punches carried thereby adapted to punch holes in said element, mechanism to rotate vsaid swinging members to locate said punches in predetermined positions, said punches being reciprocable and having heads, axially movable means to engage said heads and reciprocate said punches, said movable means having an opening therein whereby in one of said predetermined positions one of said punches is not reciprocated by the movement of said movable means, in consequence whereof said element swings to a new position of rest after one hole has been punched therein and is thereafter balanced by rocking said swinging members to new positions of adjustment and punching two holes therein.

14. In a machine to .give static balance to an out of balance element, means to support said element for free rotation,swinging members,punches carried therebyadapted to punch holes in said eley ment, mechanism to rotate said swingingmembers to locate said punches in predetermined positions, said punches being reciprocable and having heads, axially movable means to engage said heads and reciprocate said punches, said movable means having an opening therein whereby in one of said predetermined positions one of said punches is not reciprocated by the movement of said movable means, in consequence whereof said element swings to a new position of rest after one hole only has been punched therein, said mechanism operable in response to the mass of material removed and the angle of rotation of the element to locate the swinging members and the punches in position to balance the element.

REINHOLD DE WIIT. 

